Puch running hot and have to adjust the idle often

Hey team;

(1) I just got my moped street legal and took it out today for her initiation ride, I went about 1 mile to the beer store and back and when I got back I noticed the exhaust was really hot... (My leg accidentally touched it) Is it normal for an exhaust to get that hot after a 1-2 mile ride? I am about 175 lbs.

(2) I have to adjust the idle nearly every time I ride, and it still stalls at lights often.

(3) Real slow up hills and accelerating.

The ped is a Maxi (not sure what kind) 2hp 2speed. I dont know much about peds or engines and would like to try simple fixes first.

Thanks for any advise!


Re: Puch running hot and have to adjust the idle o

Two speeds often have trouble on hills.. they just dont shift when they should.. depends on the hill's slope, vehicle weight, gear ratio, etc. Not a lot can be done to make it climb steep hills better other than sprocket (final gear ratio) changes. Different clutch springs can alter where a bike shifts but that's kinda difficult to do.

Idle should be set only when the engine is good and hot. If it's adjusted on a cold engine it'll only idle when the engine is cold.

Aside from that, a clean carb.. correct float level, etc matter. And look for vacuum leaks around the intake manifold. (Spray some Starter Fluid around the area.. if the engine responds, there's a leak)

Re: Puch running hot and have to adjust the idle o

Hey joe;

Thanks for the tips.... you got me thinking - I dont recall my ped ever going into 1st gear? Maybe my ped is just starting in 2nd (this would explain slow acceleration) and never downshifting. Is there no easy way to adjust the 'sensetivity' of my gear shifting, so my ped will go into 1st gear easier?

Thanks for the help!


Re: Puch running hot and have to adjust the idle o

i really can't help with the Maxi .. i know nothing about it.. but lots of people here own them. Hang on for other people to contribute.

You should be able to hear and feel a bike shift, often accompanied by some shuddering of the 2nd gear clutch. Acceleration off the line should be good on a flat road if it's actually in 1st gear.

I knw of no easy way to adjust shift point. It depends on a centrifugal clutch who's characteristics depend on the strength of it's internal springs. These springs are sometimes replaced to tailor performance, and springs of different strengths are offered for sale.

Re: Puch running hot and have to adjust the idle o

Louie Armstrong /

Are you sure its a two speed? I used to have a one speed that would kick in around 15mph... it felt like it was shifting.

Uphills... maxi's are lackluster performers.

The exhaust pipe will burn your leg, so don;t worry about that.


Re: Puch running hot and have to adjust the idle o

my Maxi used to have the same problem, i was running very rich with my stock setup so i added a biturbo and i guess it balanced out the air/fuel ratio. i also set idle only when the engine is at operating temperature and idling problems disappeared

Re: Puch running hot and have to adjust the idle o

Thanks for all the tips.... keep them coming!

1) In regards to setting the idle when the ped is hot... good call, I was setting the idle when it was cold, and that seems to have fixed the problem.

2) MaxMagnem - I appreciate the bit about the exhaust burning you being normal...

3) Maybe the ped is just a 1 speed? In which case it is sluggish getting started and up hills.... clean the carb? Is this hard to do?



Re: Puch running hot and have to adjust the idle o

Ooops - one other thing - can anyone tell from the pic posted on my profile what kind of Puch this is.... the vin says 1978... but thats all I know.



Re: Puch running hot and have to adjust the idle o

looks almost exactly like _my_ maxi, even the color! if you can see my tranny just behind the piston, you can see that it's circular. that means that it's a 1 speed tranny. if it's more rectangular with "puch" stamped on it, it's a 2 speed.

Re: Puch running hot and have to adjust the idle o

it's a Puch Maxi 2, or the 'deluxe' model. i can tell because of the subtle differences in your taillight and the obvious one being the headlight and speedo not being a one-piece combo. i currently own the '75 Maxi Custom version made by Bombardier and have owned both of them over the years. not _too_ much difference in the two performance wise i might add

Re: Puch running hot and have to adjust the idle o

I have never seen a Puch with a one piece headlight/speedo combo, I have owned various years and models totaling at least 10 bikes and have never seen it, maybe someone else here has seen it, or mayb thats another Bombardier difference, and the taillights were all the same here I believe, except for the two styles that were used depending on year, ie up to say 76 was the square one and after 76 was the diamond(??) one(not so square). Another difference I have noticed was you guys had a different style headlight that I have never seen on a US bike.

Re: Puch running hot and have to adjust the idle o

ok, I looked through nearly every 76-79 Puch picture, I found three with headlight/speedo combos, 1 was a Kromag, and if I recall correctly Kromag was its own company under license by Puch, and the other two had square headlights, one said Bombardier, but the square headlights are non-US bikes(as far as I know), so I guess that is another difference.

That other taillight I was talking about is flat on top and bottom and round on the sides, I have never seen that in the states.

Re: Puch running hot and have to adjust the idle o

Smitty Smith /

Most Maxi's were powered by the one-speed E50 engine, while the Magnum, and some Newports, and an occasional Cobra and certain Maxi's had the two-speed za50.

From my experiences and readings, the E50 is about as close to bullet-proof as you can get from a moped engine. There are very sluggish off the line, but run great after 10-15mph, on flat ground...but again leave much to be desired as for climbing hills. It has one centrifugal clutch, usually two-shoe (after-market and later years had three-shoes). The clutch shoes are adjustable, by turning in or out the set screw above the spring in each shoe.

The "2" classification on your Maxi, more than likely refers to the 2hp engine, which should have a 14mm carb and intake, and depending on which piston/cylinder, will have a 12-14mm round intake port, or a rectangle shaped intake port.

Hope this helps.



Re: Puch running hot and have to adjust the idle o

i took some pics of my bike a few days ago, i'll post em soon so you can get a better idea of what the differences are.

in the meantime let's get back to assisting Bill with his idling problem.

Re: Puch running hot and have to adjust the idle o

2 things

If it is a 2 speed, the transmission may have too much transmission fluid in it. It is easy to ovefill 2 speed Puch trannys because the fill plug is on top of the tranny.

You can drain it (drain hex head nut under the rear of the engine (tranny). Refill it with 9.5 ounces of ATF type "F".

Second thing, the idle issue. sounds like you have a vaccum leak around the engine to intake manifold connection or the carb to intake manifold connection. It's sucking in extra air making you run lean and Hot. Make sure all the screws and bolts associated with the carb are tight (but don't overtighten).

Re: Puch running hot and have to adjust the idle o

Thanks Zippy;

1) I have come to the conclusion I have a 1 speed. So, that would explain the no shifting.... but she still is slow off the line and up hills.

2) I will go over the screws and make sure they are all tight.... I tuned the idle when the ped was hot and it does not stall nearly as much.... so maybe it is just fine tweaking from here or a small leak.

But back to the lack of power problem... I am thinking about taking the carb apart and cleaning it (seems to be common consensus on what to do) but am really pretty scared of carborators... I accidentially took the top off mine once and it took me 30 min. to get the spring and parts back in place... And that was just the top of the carb. Anyway - keep the advise comming!


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